cd to path in batch files

when running batch file from inside bin directory, prevents errors like:

d:\sources\OSS\cloud\deltacloud-core\clients\cimi\bin>start.bat
D:/Programs/Ruby193/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require': cannot load such file -- ./init.rb (LoadError)
        from D:/Programs/Ruby193/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'

and

d:\sources\OSS\cloud\deltacloud-core\server\bin>deltacloudd -i mock
Starting Deltacloud API :: mock :: http://localhost:3001/api
config.ru:17:in `load': cannot load such file -- ./lib/initialize.rb (LoadError)

This doesn't affect the deltacloudd.bat installed with gem install deltacloud-core, it's only for running DC from the source repo.